18. The genetic basis of human blood types includes recessive (Zo) and codominant alleles (ZA and ZB). Determine which of the following genotypes produce blood that agglutinates when combined with type O serum: I. ZAZAII. ZAZBIII. ZAZO

An antibody-antigen interaction involving serum and red blood cells leads to clumping or agglutination. Type O blood is the "universal donor" because the red blood cells have no antigens. However, type O serum contains anti-A and anti-B antigens. I, II and III contain red blood cells with either some A or B or both antigens, thus resulting in antibody-antigen interaction with type O serum.

I believe there is an error with this question's answer explanation. The answer states "However, type O serum contains anti-A and anti-B antigens". Shouldn't the answer be that type o serum contains type A and B anti bodies? I could be wrong, but this seems a bit shifty.